The present invention relates generally to air, smoke and fire dampers, and more particularly, to a simplified operator for use in conjunction with such dampers.
A variety of dampers have been developed for use in regulating the flow of air through a duct system, as well as for use in controlling the passage of fire or smoke through the duct system. Many duct systems are large enough to acccommodate relatively large, multiple blade-type dampers, which generally include a plurality of hinged blades disposed within a frame. The damper blades are journalled for rotation within the frame of the damper, so that the blades can be opened or closed as desired. Examples of such dampers may be found, for example, in my U.S. Pat. No. 4,113,230, dated Sept. 12, 1978, and entitled "Rotating Blade Fire Damper"; and my U.S. Pat. No. 4,113,232, dated Sept. 12, 1978, and entitled "Smoke, Fire, and Air Control Damper With Stamped Blade."
A variety of damper operators have been developed for use in regulating the positioning of the damper blades between their open and closed position. For example, the damper assemblies previously referred to incorporate an operator which generally comprises a series of brackets attached to each of the blades of the damper, and a connecting rod which is pivotally attached to each of the brackets, so that uniform articulation of the damper blades occurs in response to movement of the connecting rod. Movement of the connecting rod, and accordingly positioning of the damper blades, can then be regulated by any of a variety of control linkages, one example being the linkage shown in my U.S. Pat. No. 4,113,230.
Often, it is important to provide a damper operator which is capable of automatically responding to an external stimulus, such as the smoke or heat of a fire, so that the blades of the damper can be opened or closed, as indicated, both quickly and positively, irrespective of their existing position. One operator which has been developed for this purpose may be found in my co-pending patent application Ser. No. 16,514, filed on Mar. 1, 1979, and entitled "Quadrant Operator". The operator disclosed generally includes a shaft-type actuating means which is selectively interconnected with the connecting rod which is used to regulate movement of the damper blades by a releasing device. The releasing device permits operation of the damper between its open and closed positions during normal conditions, however, upon sensing a selected stimulus, such as heat or smoke, the releasing device is caused to disengage from the connecting rod, so that the damper blades can be urged toward a selected position by an appropriate biasing means.
Such damper operators serve well to properly operate the damper in accordance with the ambient conditions present in the duct system. However, in order to permit the damper blades to be fully rotated between their open and closed position, such damper operators must generally rotate through an arc of approximately 90.degree., so that their rotation will permit full travel of the connecting rod between its terminating positions. This requires that a sufficient amount of space be provided in order to permit free rotation of the damper operator, as well as free movement of the connecting rod between is terminating positions.
Providing sufficient space to accommodate such damper operators generally does not present a problem when relatively large dampers can be used. However, such damper operators often cannot be used in conjunction with relatively small dampers, for use in duct systems having relatively small cross-sectional dimensions. One method which has been used to overcome this difficulty is to incorporate a damper which is large enough to accommodate a conventionally sized damper operator into a duct system which has been suitably modified to accommodate the larger damper therein. This generally requires that the duct be enlarged at the position where the damper is to be installed, which leads to two major disadvantages. First, it is necessary to specially modify the duct system to accept the larger damper structure. This leads to increased installation costs, as well as increased labor. Second, it is often required that such dampers be installed within portions of the duct system which extend through the fire walls associated with a building. For this reason, it is often not possible to utilize a damper having a cross sectional dimension which exceeds that of the duct, since to do so would require enlargement of the opening in the fire wall which accommodate the duct system, which is undesirable and often not possible.
It is therefore desirable to develop a damper operator which can be used in conjunction with smaller sized dampers, in order to permit such dampers to be installed within the duct system without having to modify or enlarge the duct system.